Towards defining adequate lithium trials for individuals with mental retardation and mental illness.

Lithium has been recommended for some psychiatric conditions and/or behavior disturbances in patients with mental retardation. Components of an adequate clinical trial were described here and case studies and double-blind cases reviewed. Based on existing data, there are few guidelines for the use of lithium with this population. Of the various indicators for lithium, the most solid are for aggression, although the type of aggression is not specified: (a) achieve a serum concentration of at least 0.5 mEq/1 to 1.0 mEq/1 unless the patient responds or trial-ending side effects appear and (b) treat for 6 to 8 weeks before concluding that the patient will not respond.